P0439
PowertrainCatalystlow severityCatalyst Heater Control Circuit (Bank 2)
What P0439 Means
There is a fault in the catalyst heater control circuit on bank 2. The heater helps the converter reach operating temperature quickly for emissions.
Symptoms
- Check engine light on
- Failed emissions test
- Higher emissions on cold start
Common Causes
- Faulty catalyst heater element
- Wiring or connector damage
- Blown fuse or relay
- Bad PCM
Diagnostic Steps
- Retrieve code and freeze frame
- Inspect heater circuit wiring and fuse
- Test heater element resistance
- Repair circuit or replace component
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Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
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Serious DIY~$100
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Autel MaxiCOM MK808S →
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✓ Autel official store
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Autel MaxiSys MS906 Pro →
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✓ Autel official store
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